1. Field of the Invention
The invention relates to a time-base correction applied when an electric signal, for example a video signal, is read from a magnetic record carrier by means of a helical scan video recorder.
2. Description of the Related Art
The magazine "Monitor-Proc. IREE" of Apr. 1976, pp. 118-122, describes such a time-base correction. The time-base errors are corrected in such a way that the video signal, which exhibits time-base errors after being read, is digitized with a variable sampling rate and is stored in a memory with the same variable frequency. Subsequently, the video signal stored in the memory is read out with a fixed frequency. The variable sampling rate, and hence the read-in frequency, is generated depending on the instantaneous time-base error. Read-out of the memory results in a video signal which is rid of time-base errors and which can subsequently be reconverted into an analog video signal for display on a TV screen.
The invention aims at providing a device for generating a variable sampling rate frequency and read-in frequency depending upon the time-base errors. The paper entitled "An Analog Segment Recording System for Home Use MUSE VTR" by Owashi et al, read to the "Technical group on video recording of ITEJ" in Tokyo on Aug. 29, 1985 (paper VR 70-4), describes a device for deriving a sampling rate from an electric signal, for example a video signal, which device comprises an input terminal for receiving the electric signal, which input terminal is coupled to an input of a synchronizing signal separator which is constructed to derive a synchronizing signal from the electric signal applied to its input and to supply the synchronizing signal to an output coupled to a first input of a phase comparator of a phase-locked loop, which further comprises a voltage-controlled oscillator having an input coupled to an output of the phase comparator, an output of the oscillator being coupled to an output terminal of the device, to supply the variable sampling rate, and to an input of a frequency divider comprising a counter, an output of the frequency divider being coupled to a second input of the phase comparator. The sampling rate generated by the known device is susceptible to interference.